Question

A bulb marked 12 V, 24 W operates 12 volt battery for 20 minutes. The energy consumed is:

• A. $28800J$
• B. $360000J$
• C. $25660J$
• D. $144000J$

Answer 1

The correct option is A $28800J$

Energy ($power\times time$) is measured in Joules and by including time (t) in the power formulae, the energy dissipated by a component or circuit can be calculated.

Energy dissipated Q= Pt.

In the question, the time taken is given as 20 minutes, that is $20\times 60=1200seconds$ and the power is 24 W.

Hence, the energy consumed by the bulb is $24W\times 1200s=28,800Joules$.